共查询到20条相似文献,搜索用时 6 毫秒
1.
Niladevi KN Sukumaran RK Prema P 《Journal of industrial microbiology & biotechnology》2007,34(10):665-674
Laccase production from a novel actinobacterial strain, Streptomyces psammoticus, MTCC 7334 was optimized in solid-state fermentation. The process parameters were initially optimized by the conventional
“one factor at a time” approach, and the optimal levels of the factors that had considerable influence on enzyme production
were identified by response surface methodology. Rice straw was identified as a suitable substrate for laccase production
(17.3 U/g), followed by coffee pulp (15.8 U/g). Other optimized conditions were particle size, 500–1,000 μm (21.2 U/g); initial
moisture content, 65% (26.8 U/g); pH of moistening solution, 8.0 (26.9 U/g); incubation temperature, 32°C (27.6 U/g) and inoculum
size, 1.5 × 107 CFU (33.8 U/g). Yeast extract served as the best nitrogen source (34.8 U/g). No enhancement in enzyme yield was observed
with carbon supplementation. The level of yeast extract, inoculum size and copper sulphate were optimized statistically. Statistical
optimization performed using a central composite design resulted in threefold increase in laccase activity (55.4 U/g) as compared
to the unoptimized medium (17.3 U/g). The upgrading of fermented rice straw for fodder enhancement is also discussed briefly. 相似文献
2.
Summary Spore production of Coniothyrium minitans was optimized by using response surface methodology (RSM), which is a powerful mathematical approach widely applied in the optimization of fermentation process. In the first step of optimization, with Plackett–Burman design, soluble starch, urea and KH2PO4 were found to be the important factors affecting C. minitans spore production significantly. In the second step, a 23 full factorial central composite design and RSM were applied to determine the optimal concentration of each significant variable. A second-order polynomial was determined by the multiple regression analysis of the experimental data. The optimum values for the critical components for the maximum were obtained as follows: soluble starch 0.643 (36.43 g. l−1), urea −0.544 (3.91 g l−1) and KH2PO4 0.049 (1.02 g l−1) with a predicted value of maximum spore production of 9.94 × 109 spores/g IDM. Under the optimal conditions, the practical spore production was 1.04 × 1010 spores/g IDM. The determination coefficient (R2) was 0.923, which ensure an adequate credibility of the model. 相似文献
3.
Optimization of riboflavin production by recombinant <Emphasis Type="Italic">Bacillus subtilis</Emphasis> RH44 using statistical designs 总被引:3,自引:0,他引:3
A sequential optimization strategy, based on statistical experimental designs, was used to enhance the production of riboflavin
by recombinant Bacillus subtilis RH44. In the first instance, the medium components were optimized in shake flask cultures. After preliminary experiments
of nitrogen source selection, the two-level Plackett–Burman (PB) design was implemented to screen medium components that significantly
influence riboflavin production. Among the 15 variables tested, glucose, NaNO3, K2HPO4, ZnSO4, and MnCl2 were identified as the most significant factors (confidence levels above 95%) for riboflavin production. The optimal values
of these five variables were determined by response surface methodology (RSM) based on the central composite design (CCD).
The validity of the model developed was verified, and the optimum medium led to a maximum riboflavin concentration of 6.65 g/l,
which was 44.3 and 76.4% higher than the improved medium and the basal medium, respectively. A glucose-limited fed-batch culture
profile in a 5-l fermentor was consequently designed according to the above optimum medium in shake flasks. A final riboflavin
concentration of 16.36 g/l was obtained in 48 h, which further verified the practicability of this optimum strategy. 相似文献
4.
Iturin A, a lipopeptide antibiotic produced by Bacillus subtilis RB14-CS, suppresses the growth of various plant pathogens. Here, enhancement of iturin A production in solid-state fermentation
(SSF) on okara, a soybean curd residue produced during tofu manufacturing, was accomplished using statistical experimental
design. Primary experiments showed that the concentrations of carbon and nitrogen sources were the main factors capable of
enhancing iturin A production, whereas initial pH, initial water content, temperature, relative humidity, and volume of inoculum
were only minor factors. Glucose and soybean meal were the most effective among tested carbon and nitrogen sources, respectively.
Based on these preliminary findings, response surface methodology was applied to predict the optimum amounts of the carbon
and nitrogen sources in the medium. The maximum iturin A concentration was 5,591 μg/g initial wet okara under optimized condition.
Subsequent experiments confirmed that iturin A production was significantly improved under the predicted optimal medium conditions.
The SSF product generated under the optimized conditions exhibited significantly higher suppressive effect on the damping-off
of tomato caused by Rhizoctonia solani K-1 compared with the product generated under the non-optimized conditions. 相似文献
5.
Fermentation conditions were statistically optimized for producing extracellular xylanase by Aspergillus niger SL-05 using apple pomace and cotton seed meal. The primary study shows that culture medium with a 1:1 ratio of apple pomace and cotton seed meal (carbon and nitrogen sources) yielded maximal xylanase activity. Three significant factors influencing xylanase production were identified as urea, KH(2)PO(4), and initial moisture content using Plackett-Burman design study. The effects of these three factors were further investigated using a design of rotation-regression-orthogonal combination. The optimized conditions by response surface analysis were 2.5% Urea, 0.09% KH(2)PO(4), and 62% initial moisture content. The analysis of variance indicated that the established model was significant (P < 0.05), "while" or "and" the lack of fit was not significant. Under the optimized conditions, the model predicted 4,998 IU/g dry content, whereas validation experiments produced an enzymatic activity of xylanase at 5,662 IU/g dry content after 60 h fermentation. This study innovatively developed a fermentation medium and process to utilize inexpensive agro-industrial wastes to produce a high yield of xylanase. 相似文献
6.
The effects of cultivation medium compositions including soybean meal, peptone, soybean oil and cornstarch for actinomycin X2 production by Streptomyces spp JAU4234 were accessed by using response surface methodology. The 2(4) full factorial designs and the paths of steepest ascent were effective in searching for the major factors of actinomycin X2 production. In this study, cornstarch and soybean oil showed negative effect on actinomycin X2 production based on the first-order regression coefficients derived from MINITAB software. Subsequently, a central composite design for optimization was further investigated. Preliminary studies showed that soybean meal and peptone were believed to be the major factors for actinomycin X2 production. Estimated optimum compositions for the production of actionmycin X2 were as follows (g/l): soybean meal 21.65 and peptone 9.41, and result in a maximum actionmycin X2 production of 617.4 mg/l. This value was closed to the 612 mg/l actionmycin X2 production from actual experimental observations. The yield of actionmycin X2 was increased by 36.9% by culturing the strain Streptomyces spp JAU4234 in the nutritionally optimized fermentation medium. 相似文献
7.
Lecanicillium muscarium is a widely occurring entomopathogenic fungus. Laboratory studies were conducted to determine the efficacy of L. muscarium against different instars of Bemisia tabaci on tomato and verbena foliage after two incubation times (3 and 7 days). Significant reduction in B. tabaci numbers were recorded on fungus treated plants (p < 0.001). Second instar B. tabaci proved most susceptible to L. muscarium infection. There was no significant difference in mortality of B. tabaci second instars after either 3 or 7 days exposure to L. muscarium on either host plant. The importance of the speed of pest mortality following treatment and the potential of L. muscarium to be incorporated into an integrated pest management strategy for the biocontrol of B. tabaci on tomato and verbena plants are discussed. 相似文献
8.
Growth and sporulation of Verticillium lecanii on inert and organic carriers (sugar-cane bagasse, corncob, rice straw, polyurethane foam and activated carbon) in a solid-state
fermentation process was studied. Sugar-cane bagasse and polyurethane foam produced 1010 spores g−1 dry carrier whereas corncob, rice straw, and activated carbon yielded, respectively 8 × 109, 4 × 109, and 3 × 108 spores g−1. Chitinase activity of the conidia was in the following order: sugar-cane bagasse (3.3 U mg−1) > wheat bran (3.0 U mg−1) > polyurethane foam (2.7 U mg−1). There was no significant difference (2.5–2.7 U mg−1) in the proteinase activity among the conidia from the three cultures. Scanning electron microscopy shows that aerial mycelium
freely penetrated into the internal area of polyurethane foam. Sugar-cane bagasse provided enough area for vegetative hyphae
to attach. Of the carriers analyzed, polyurethane foams and sugar-cane bagasse were the best carriers for V. lecanii growth and spore production. 相似文献
9.
The potential for using the entomopathogenic fungus Lecanicillium muscarium to control the sweetpotato whitefly, Bemisia tabaci has been established in the laboratory by other studies. Laboratory studies however frequently overestimate the level of
control achieved by biological control agents in the glasshouse. Before full-scale commercial or field development is considered,
glasshouse trials are required to confirm laboratory results. Under both controlled laboratory and glasshouse conditions high
mortality of second instar B. tabaci was recorded after application of L. muscarium. The potential of incorporating L. muscarium into integrated pest management strategies for the control of B. tabaci is discussed. 相似文献
10.
Basar Uyar Matthias Schumacher Jakub Gebicki Michael Modigell 《Bioprocess and biosystems engineering》2009,32(5):603-606
Rhodobacter capsulatus was used for the phototrophic hydrogen production on effluent solution derived from the thermophilic fermentation of Miscanthus
hydrolysate by Thermotoga neapolitana. Pretreatments such as centrifugation, dilution, buffer addition, pH adjustment and sterilization were suggested for the
effluent before being fed to the photofermentation. Batch-wise experiments showed that R. capsulatus grows and produces hydrogen on the pretreated effluent solution. Moreover, it was found that the hydrogen yield increased
from 0.3 to 1.0 L/Lculture by addition of iron to the effluent solution. 相似文献
11.
Jeong Jun Kim 《BioControl》2007,52(6):789-799
The activity of entomopathogens on insect pests has been investigated for many species but the influence of entomopathogenic
fungi on factors other than mortality relating to population increase has not been frequently studied. The influence of Lecanicillium attenuatum CS625 (=Verticillium lecanii CS625) on development and reproduction of cotton aphid (Aphis gossypii) was investigated. A conidia suspension of the isolate was applied onto first instar nymphs. Increased spore concentration
did not significantly affect each nymphal stage, total nymphal period, pre-reproductive period and the age of first larviposition.
A significant dose effect on reduction of life span, reproductive period and fecundity was observed in 1st and 3rd instars
after spore application. When conidia were applied to 1st instars, life span was significantly reduced to 10.8 and 8.4 days
at 1 × 104 and 1 × 108 conidia/ml, respectively from 12.2 days in the control. During the life span, total fecundity was 41 ± 7.3, 26 ± 0.8 and
22 ± 5.7 nymphs per female at 1 × 104, 1 × 106 and 1 × 108 conidia/ml, respectively compared with 51 ± 2.0 nymphs per untreated female. Reproduction period was also significantly shortened
with increasing spore concentration. Application of spores to 3rd instars showed a similar trend. However, daily fecundity
of individual aphids was not affected by spore dose. It was concluded that the isolate of L.
attenuatum is able to affect populations of cotton aphid by reducing life span and total fecundity as well as by killing the aphids
directly. 相似文献
12.
Glucoamylase production by a thermophilic mold Thermomucor indicae-seudaticae was optimized in solid-state fermentation (SSF) by conventional one variable at a time approach and further statistically using response surface methodology (RSM). Glucoamylase secretion was strongly affected by three variables (moisture ratio, inoculum level and incubation time), and therefore, these three factors were further optimized using response surface methodology. The glucoamylase production in flasks containing wheat bran, under the conditions optimized by RSM, was 455 ± 23 U/g of dry moldy bran (DMB), while the predicted value by a polynomial model was 433.30 U/g DMB. The enzyme titre (455 ± 23 U/g DMB) attained in the validation experiment of this investigation is higher than those reported in the literature. When the large-scale production was attempted in enamel trays, a marginally lower enzyme titres were attained. An overall 1.8-fold increase in glucoamylase production was achieved in SSF due to statistical optimization in comparison with that of one variable at a time approach (250 ± 13 U/g DMB). A 10-fold enhancement in glucoamylase production was recorded in SSF as compared to that in submerged fermentation. 相似文献
13.
G. Amin S. Alotaibi Narmen A. Youssef W. D. Saleh 《World journal of microbiology & biotechnology》2008,24(11):2465-2471
In an attempt to develop a cost-effective process for bioinsecticide production by B. thuringiensis, the feeding regime during aerobic cultivation of the bacterium was investigated and optimized. The process was designed
as a two-stage process; a first stage of active growth, where glucose and other nutrients were adequately supplied to the
growing cells over 12 h, followed by a second stage of 2 h for spore formation and toxin release. In order to maximize spore
and toxin yield and productivity, different quantities of glucose and nutrients were fed separately to the growing cells in
four different fermentation runs. In all runs, glucose was converted to bacterial biomass during the first stage and subsequently
to spores and crystal protein during the second phase. The best results were obtained with a fermentation run supplied with
190 g glucose in 1500 ml. Up to 20.1 g of bacterial insecticides/l were recovered from fermentation broth with a glucose to
toxin conversion yield of 0.159 g/g. Also, a markedly high spore concentration of 2.31 × 1012 c.f.u./ml was obtained. The spore–crystal protein mixture obtained was tested for its insecticidal activity against three
of the most agronomically important pests. Among the bioinsecticide-treated insect pests, Egyptian cotton leafworm, Spodoptera littoralis was the most susceptible pest with the lowest LC50 of the bioinsecticides against its larval instar and the highest virulence against adults emerged later on from the surviving
larvae. 相似文献
14.
Bussari B Saudagar PS Shaligram NS Survase SA Singhal RS 《Journal of industrial microbiology & biotechnology》2008,35(1):49-58
Cephamycin C is an extracellular broad spectrum β-lactam antibiotic produced by Streptomyces clavuligerus, S. cattleya and Nocardia lactamdurans. In the present study, different substrates for solid-state fermentation were screened for maximum cephamycin C production
by S. clavuligerus NT4. The fermentation parameters such as substrate concentration, moisture content, potassium dihydrogen phosphate, inoculum
size and ammonium oxalate were optimized by response surface methodology (RSM). The optimized conditions yielded 21.68 ± 0.76 mg gds−1 of cephamycin C as compared to 10.50 ± 1.04 mg gds−1 before optimization. Effect of various amino acids on cephamycin C production was further studied by using RSM, which resulted
in increased yield of 27.41 ± 0.65 mg gds−1. 相似文献
15.
Bacillus licheniformis was grown for 48 h at 37°C in solid state fermentation; a maximum of 1.7 × 1011 spores/g dry substrate were obtained using rice straw powder (300 g/kg) and wheat bran (700 g/kg) supplemented with glucose
(40 g/kg), peptone (20 g/kg), yeast extract (20 g/kg), KH2PO4 (10 g/kg) and CaO (5 g/kg) with an initial moisture content of 65%. 相似文献
16.
Lovastatin, an inhibitor of HMG-CoA reductase, was produced by submerged fermentation using Monascus purpureus MTCC 369. Five nutritional parameters screened using Plackett–Burman experimental design were optimized by Box–Behnken factorial
design of response surface methodology for lovastatin production in shake flask cultures. Maximum lovastatin production of
351 mg/l were predicted in medium containing 29.59 g/l dextrose, 3.86 g/l NH4Cl, 1.73 g/l KH2PO4, 0.86 g/l MgSO4·7H2O, and 0.19 g/l MnSO4·H2O using response surface plots and point prediction tool of DESIGN EXPERT 7.0 (Statease, USA) software. 相似文献
17.
The maT clade of transposons is a group of transposable elements intermediate in sequence and predicted protein structure to mariner and Tc transposons, with a distribution thus far limited to a few invertebrate species. We present evidence, based on searches of publicly available databases, that the nematode Caenorhabditis briggsae has several maT-like transposons, which we have designated as CbmaT elements, dispersed throughout its genome. We also describe two additional transposon sequences that probably share their evolutionary history with the CbmaT transposons. One resembles a fold back variant of a CbmaT element, with long (380-bp) inverted terminal repeats (ITRs) that show a high degree (71%) of identity to CbmaT1. The other, which shares only the 26-bp ITR sequences with one of the CbmaT variants, is present in eight nearly identical copies, but does not have a transposase gene and may therefore be cross mobilised by a CbmaT transposase. Using PCR-based mobility assays, we show that CbmaT1 transposons are capable of excising from the C. briggsae genome. CbmaT1 excised approximately 500 times less frequently than Tcb1 in the reference strain AF16, but both CbmaT1 and Tcb1 excised at extremely high frequencies in the HK105 strain. The HK105 strain also exhibited a high frequency of spontaneous induction of unc-22 mutants, suggesting that it may be a mutator strain of C. briggsae. 相似文献
18.
Nehme N Mathieu F Taillandier P 《Journal of industrial microbiology & biotechnology》2008,35(7):685-693
This study examines the interactions that occur between Saccharomyces cerevisiae and Oenococcus oeni strains during the process of winemaking. Various yeast/bacteria pairs were studied by applying a sequential fermentation strategy which simulated the natural winemaking process. First, four yeast strains were tested in the presence of one bacterial strain leading to the inhibition of the bacterial component. The extent of inhibition varied widely from one pair to another and closely depended on the specific yeast strain chosen. Inhibition was correlated to weak bacterial growth rather than a reduction in the bacterial malolactic activity. Three of the four yeast strains were then grown with another bacteria strain. Contrary to the first results, this led to the bacterial stimulation, thus highlighting the importance of the bacteria strain. The biochemical profile of the four yeast fermented media exhibited slight variations in ethanol, SO(2) and fatty acids produced as well as assimilable consumed nitrogen. These parameters were not the only factors responsible for the malolactic fermentation inhibition observed with the first bacteria strain. The stimulation of the second has not been reported before in such conditions and remains unexplained. 相似文献
19.
Tanino T Aoki T Chung WY Watanabe Y Ogino C Fukuda H Kondo A 《Applied microbiology and biotechnology》2009,82(1):59-66
Previous studies have demonstrated the efficacy of our Bacillus cereus isolate (NRRL 100132) in reducing concentrations of nitrogenous wastes and inhibiting growth of fish pathogens. In vivo efficacy
and tolerance to a range of physiological conditions in systems used to rear Cyprinus carpio make this isolate an excellent candidate for aquaculture applications. Production cost is an important consideration in development
of commercially relevant biological products, and this study examines the optimization of nutrient supplementation, which
has an impact on high-density production of spores by fermentation. Corn steep liquor (CSL) was identified as a lower cost
and more effective nutrient source in comparison to conventional nutrient substrates, in particular yeast extract and nutrient
broth. The improved sporulation performance of B. cereus could be related to the increased availability of free amino acids, carbohydrates, and minerals in CSL, which had a positive
effect on sporulation efficiency. The impact of nutrient concentration on spore yield and productivity was modeled to develop
a tool for optimization of nutrient concentration in fermentation. An excellent fit of the model was confirmed in laboratory
fermentation studies. A cost comparison revealed that production using liquid phytase and ultrafiltered-treated CSL was less
expensive than spray-dried CSL and supported cultivation of B. cereus spores at densities higher than 1 × 1010 CFU ml−1. 相似文献
20.
Seventeen isolates of Metarhizium anisopliae (Metschnikoff) Sorokin and two isolates of Beauveria bassiana (Balsamo) Vuillemin were evaluated for their pathogenicity against the tobacco spider mite, Tetranychus evansi Baker & Pritchard. In the laboratory all the fungal isolates were pathogenic to the adult female mites, causing mortality between 22.1 and 82.6%. Isolates causing more than 70% mortality were subjected to dose–response mortality bioassays. The lethal concentration causing 50% mortality (LC50) values ranged between 0.7×107 and 2.5×107 conidia ml−1. The lethal time to 50% mortality (LT50) values of the most active isolates of B. bassiana and M. anisopliae strains varied between 4.6 and 5.8 days. Potted tomato plants were artificially infested with T. evansi and treated with B. bassiana isolate GPK and M. anisopliae isolate ICIPE78. Both fungal isolates reduced the population density of mites as compared to untreated controls. However, conidia formulated in oil outperformed the ones formulated in water. This study demonstrates the prospects of pathogenic fungi for the management of T. evansi. 相似文献